In general, the invention relates to wireless communication systems. More specifically, the invention relates to cellular communications and in particular, to a method and system for channel estimation within cellular communications.
For optimal reception of a digital signal over a broadband cellular channel, the channel to a desired transmitter must be determined. Because channels can consist of a number of multipath components or rays each with its own time of arrival and Doppler frequency, a channel estimator should determine the actual time of arrivals (TOA""s), Doppler frequencies, and their corresponding complex gains. The channel estimator should also adapt to many different transmitting environments where there are a very large number of rays with a TOA spread and a Doppler frequency spread. A maximum likelihood (ML) channel estimation approach as is known in the art, may provide the best TOA and Doppler frequency estimates, however it lacks a closed form solution.
Prior art TOA estimators such as a TOA estimation using ESPRIT, are not robust to channel conditions with a large number of rays with a TOA spread and are not suitable for multi-user channel estimation. Other channel estimators may assume a worst-case channel and thus need to estimate many more parameters than is necessary under typical channel conditions.
Thus, there is a significant need for a method and device for improving multi-user channel estimation techniques that overcome the above disadvantages and shortcomings, as well as other disadvantages.